woensdag 26 oktober 2011

Cacao Diseases in Central America 5

The Tropical Agricultural Research and Higher Education Center (CATIE) is a regional center dedicated to research and graduate education in agriculture and the management, conservation and sustainable use of natural resources.
Its members include the Inter-American Institute for Cooperation on Agriculture (IICA), Belize, Bolivia, Colombia, Costa Rica, the Dominican Republic, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Venezuela and Spain.
Source:  Tropical Agricultural Research and Higher Education Center, CATIE, 2009.


Other cacao diseases
Thread blight    The fungus Pellicularia koleroga produces whitish mycelia threads that spread over the stems and leaves.
The leaves dry out and detach but remain suspended on the branches by the mycelia. The disease seldom causes major damage, but in extreme conditions it can kill the branches.
Thread blight occurs in abandoned plantations or in excessively shaded plantations. It is spread via direct contact, insects and work tools.
Good plantation management prevents and controls the disease. An effective way to combat it is by cutting and eliminating diseased branches and
then disinfecting the tools used.
Pink disease   The fungus Corticium salmonicolor attacks the branches, twigs and trunk of the cacao tree, covering them with a white crust that later turns pink. It causes defoliation, drying of the branches and, in very few cases, the death of the tree.  It usually occurs in young, dispersed trees in the plantation, which means that its economic impact is limited. The fungus is spread by windborne spores and survives in old lesions. This disease can be combated using a similar method to that for thread blight.

Galls or warts    These are growth abnormalities that occur on the trunk and branches of cacao and are known as green-point galls, flowery galls, fan galls, knob galls and lobed galls. The most studied is the green-point gall caused by Albonectria rigidiuscula.
This fungus produces a large number of very small shoots that do not develop and affect the growth and fruiting of the plant. The propagation of these diseased plants should be avoided. Highly damaged plants should be completely eliminated.
Warning!    Witches’ broom is a threat
This is one of the most damaging cacao diseases and is caused by the fungus Moniliophthora perniciosa (formerly Crinipellis perniciosa). It attacks all cacao plants, causing abnormal growths and lesions on the shoots, branches, floral cushions and fruits. It also attacks nursery seedlings. Some of the symptoms on the fruits can be confused with moniliasis.
Witches’ broom is present in South America, some Caribbean countries and areas south of the Panama Canal, which means it is a permanent threat to Central American cacao plantations.
The early identification of witches’ broom is essential in order to alert the appropriate authorities and prevent the spread of this disease in the region. The fungus can propagate in any kind of tissue such as seeds, whole plants, twigs, fruits, etc.
How do we recognize witches’ broom?
Brooms on the floral cushions
Brooms and dry fruits
Green brooms on shoots
Small pink umbrellas appear on dead tissues and then turn brown as they form millions of spores underneath
Infection of the chocolate (Theobroma cacao) tree and pods by cacao pathogens Moniliophthora (Crinipellis) perniciosa and Moniliophthora roreri. a. Witches’ broom of plant stems caused by M. perniciosa infection. b. Chocolate pods and seeds infected with M. perniciosa. c, d. Frosty pod rot caused by M. roreri on pods and seeds.

Do not put your plantation or your country at risk.
Do not introduce cacao plants or any plant parts (fruits, seeds, twigs or buds)
from South America or any other affected country.

If you see any symptoms of witches’ broom on your plantation, do not move
any vegetative material and immediately contact officials of the Ministry of Agriculture, the National Plant Protection Office, or other related institution.
Bibliography Capriles, L. Enfermedades del cacao en Venezuela. Fondo Nacional de cacao, Venezuela.
Hill, DS, and Waller, JM. 1988. Pests and diseases of tropical crops. Singapore, Longman. Porras U., VH. 1988. Enfermedades del cacao. La Lima, Honduras. FHIA: Serie Tecnología Comunicación y Desarrollo Fascículo
Rossman, A; Palm, M, and Spielman, LJ. 1990. A literature guide for the identification of plant pathogenic fungi. APS press, Minnesota, USA.
Wellman, FL. 1977. Dictionary of tropical crops and their diseases. New York, Scarecrow.
Wood, GR. 1982. Cacao. Translation from English by Antonio Marino, México, Continental.